the case for /rescue

ucsdboy

ucsdboy

Hi guys,

I was thinking recently that with boot environments + live usb drives, has the /rescue directory become a little redundant?
 
A: Not everyone uses ZFS; lots of systems use UFS for the root.

B: A live USB drive may have be set up before the system fails, if the system is the one that would be used to set it up. Do we want to say that every FreeBSD installation shall have a rescue USB drive ready to go?

C: The amount of disk space used by /rescue is tiny; du tells me 8M.
 
Ty for the reply! Specifically to your point B, the generic usb image or iso isn’t enough to start FreeBSD and mount your system disk to fix? I’m trying to think of scenarios where this wouldn’t be enough.
 
ucsdboy said:
Ty for the reply! Specifically to your point B, the generic usb image or iso isn’t enough to start FreeBSD and mount your system disk to fix? I’m trying to think of scenarios where this wouldn’t be enough.
Click to expand...
In almost all circumstances it will be enough, but that's of little consolation if you don't have one at hand.
 
ucsdboy said:
Ty for the reply! Specifically to your point B, the generic usb image or iso isn’t enough to start FreeBSD and mount your system disk to fix? I’m trying to think of scenarios where this wouldn’t be enough.
Click to expand...
As adorno said: How do I make one, if my only system is down? Or the system that provides network connectivity? Or I don't have a USB stick at home? Or my computer doesn't have a functioning USB port, or I'm missing the required adapter from USB-x to USB-y? Or if booting from USB was turned off for security reasons?

Occam lives!
 
Another edge case, from rescue(8):

… To build a FreeBSD system where space is critical, /rescue can be used as a replacement for the standard /bin and /sbin directories; … Since /rescue is statically linked, it should also be possible to dispense with much of /usr/lib in such an environment. …
Click to expand...

ralphbsz said:
C: The amount of disk space used by /rescue is tiny; du tells me 8M.
Click to expand...

Two files, one of which is 18M and has 149 hard links.

du -hs /rescue might find more space used on UFS.

FreeBSD 15.0-CURRENT 1500023 on ZFS:

Code: 
% ls -l /bin /sbin | wc -l
     201
% du -h /bin /sbin
773K    /bin
3.7M    /sbin
% du -hs /usr/lib
1.8G    /usr/lib
% du -hs /rescue
8.4M    /rescue
%

Code: 
% eza --long --header --links --sort=inode --reverse --no-permissions --no-time --no-user /rescue
Links Size Name
    1 9.9k dhclient-script
  149  18M csh
  149  18M zstdmt
  149  18M restore
  149  18M dump
  149  18M dd
  149  18M pfctl
  149  18M stty
  149  18M unzstd
  149  18M fsck
  149  18M nextboot
  149  18M rm
  149  18M zstd
  149  18M ccdconfig
  149  18M fsck_ufs
  149  18M nos-tun
  149  18M sed
  149  18M kldload
  149  18M ln
  149  18M zcat
  149  18M unxz
  149  18M kenv
  149  18M geom
  149  18M tee
  149  18M less
  149  18M mount_msdosfs
  149  18M bunzip2
  149  18M kldconfig
  149  18M iscsictl
  149  18M red
  149  18M gpart
  149  18M fsirand
  149  18M sleep
  149  18M bectl
  149  18M realpath
  149  18M gzip
  149  18M dhclient
  149  18M iscsid
  149  18M cp
  149  18M hostname
  149  18M [
  149  18M mt
  149  18M chmod
  149  18M fsck_msdosfs
  149  18M rdump
  149  18M devfs
  149  18M whoami
  149  18M gzcat
  149  18M sync
  149  18M gunzip
  149  18M zfsbootcfg
  149  18M tail
  149  18M ed
  149  18M mknod
  149  18M ldconfig
  149  18M fasthalt
  149  18M ls
  149  18M reboot
  149  18M kill
  149  18M savecore
  149  18M chio
  149  18M route
  149  18M rrestore
  149  18M kldstat
  149  18M mount_nfs
  149  18M rmdir
  149  18M echo
  149  18M rtquery
  149  18M fsdb
  149  18M bzip2
  149  18M chown
  149  18M swapon
  149  18M pgrep
  149  18M cat
  149  18M poweroff
  149  18M id
  149  18M nc
  149  18M ifconfig
  149  18M mount_udf
  149  18M newfs_msdos
  149  18M disklabel
  149  18M chgrp
  149  18M setfacl
  149  18M more
  149  18M dmesg
  149  18M mdconfig
  149  18M ipf
  149  18M ipfw
  149  18M routed
  149  18M newfs
  149  18M sh
  149  18M fastboot
  149  18M fsck_ffs
  149  18M link
  149  18M getfacl
  149  18M halt
  149  18M unlink
  149  18M tar
  149  18M head
  149  18M zdb
  149  18M ex
  149  18M groups
  149  18M sysctl
  149  18M mount_unionfs
  149  18M ps
  149  18M pkill
  149  18M bsdlabel
  149  18M umount
  149  18M mdmfs
  149  18M dumpfs
  149  18M vi
  149  18M zpool
  149  18M dumpon
  149  18M xzcat
  149  18M test
  149  18M kldunload
  149  18M ping
  149  18M init
  149  18M chroot
  149  18M mv
  149  18M glabel
  149  18M rescue
  149  18M tcsh
  149  18M zstdcat
  149  18M rtsol
  149  18M md5
  149  18M tunefs
  149  18M fsck_4.2bsd
  149  18M ping6
  149  18M fetch
  149  18M pwd
  149  18M mkdir
  149  18M fdisk
  149  18M shutdown
  149  18M expr
  149  18M clri
  149  18M mount_nullfs
  149  18M unlzma
  149  18M xz
  149  18M df
  149  18M camcontrol
  149  18M lzma
  149  18M mount_cd9660
  149  18M mount
  149  18M lzcat
  149  18M rcorder
  149  18M zfs
  149  18M bzcat
  149  18M chflags
  149  18M date
%
 
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